【作者】 孙兴国；

【导师】 刘建明；

【作者基本信息】 中国科学院研究生院（地质与地球物理研究所） ， 矿物学、岩石学、矿床学， 2008， 博士

【摘要】 近年来的研究表明,大兴安岭中南段成矿带具海西期和燕山期两期成矿特征,区内多数矿床与二叠系地层关系密切,2004年新发现的龙头山矿床即为产于其东坡二叠系地层的一个资源潜力可观的Ag-Pb-Zn多金属矿床。该矿床成矿区位优越,研究历史处于空白,具有重要研究价值。本论文在深入细致地野外地质工作基础上,确立了其“两期成矿,三类矿化”的地质特征,进而通过微量、稀土元素,硫、铅、锶同位素等矿床地球化学研究,以及流体包裹体岩相学、显微测温、激光拉曼分析和包裹体热力学计算等研究,探讨了其成矿物质和成矿流体的来源及特征,并且尝试将单颗粒Rb-Sr等时线测年新技术用于确定其成矿时代。在上述工作基础上,开展了比较矿床学研究,并总结了成矿控制因素和地质找矿标志,最后建立了该矿床的成矿模式和找矿模型,并据此提出下一步找矿工作方向。论文取得的主要成果如下:1、龙头山矿床经历了热水沉积-热液改造两期成矿作用,共发育(似)层状、脉状(透镜状)和筒柱状三类矿化,其主成矿期为热水沉积成矿期。2、矿床地球化学研究表明,金属硫化物具热水沉积成矿作用特征,但普遍受后期热液改造作用影响;重晶石矿物同位素组成均一,具海底热水沉积成因特征;灰岩、凝灰岩等围岩是成矿物质来源之一;Pb模式年龄以及Rb-Sr等时线研究均得出比地层更老的年龄值,可能是因为受热液改造期影响,并有古老基底物质带入。3、龙头山矿床重晶石矿物中的流体包裹体主要为富气相(C型)和富液相(D型)两种类型,大小均为2～7um,包裹体成分以H2O为主。两类包裹体冰点温度为-5.5℃～-0.3℃和-7.1℃～-2.4℃;盐度为0.5～8.5wt%和4.0～10.6wt%;均一温度为101.4℃～279.9℃和176.8℃～361.6℃,其峰值在170℃和270℃附近。成矿流体的密度为0.73～0.97g/cm3,成矿压力为62.3×105～377.9×105Pa,推测成矿深度为0.62～3.78Km。包裹体的上述特征与海底热水沉积型矿床的特征比较符合。4、通过比较研究,认为龙头山矿床具备热水沉积型矿床的主要特征,总结了矿床的控矿因素和找矿标志,建立成矿模式和找矿模型,最后提出了下一步找矿工作方向。更多还原

【Abstract】 The recent years research indicated that middle-south section of Da Hinggan Mountains metallogenic belt has two periods(Hercynian and Yanshanian) characteristics of metallogenesis, as well as the most of ore deposits in the area closely relate to Permian strata. Longtoushan ore deposit discovered in 2004 is an Ag-Pb-Zn polymetallic ore deposit born in Permian and located in the east hillside of the metallogenic belt, which has considerable resources potentials. It has important research value for its good metallogenic location and blank research history. Base on the detail field geology studies, the geology characteristics of“two stages and three kinds of metallogensis”has established. According to further work through geochemistry research including trace element,REE, S, Pb and Sr isotope,as well as petrography, microtemperature measurement, Laser Raman analysis and thermodynamics calculation of fluid inclusion, origin and characteristic of the ore-forming material and fluid has been discussed. And a new technology of single pellet Rb-Sr isochrones has been tried for dating its born time. Base on above work, study of ore deposit comparison has been carried out, and metallogensis controlling factor and geological prospecting symbol have been summarized. Finally, metallogenic model and prospecting model have been established. According to above, the next step work direction has been proposed. Main achievement of the paper are listed as follow:1、Longtoushan ore deposit has experienced two metallogenic periods including hot-water sedimentation period and hydrothermal reformation period. There are three kinds of metallizing phase: bedded(or near-bedded) phase, vein-shaped phase and pipe-shaped phase. The main metallogenic period is hot-water sedimentation period.2、Ore deposit geochemistry research indicated that the metal sulfides have characteristic of hot-water sedimentation metallogensis, but generally suffered later hydrothermal transformation. The barite mineral isotopic content is homogeneous, showing the seabed hot-water sedimentation origin characteristic. Wall rock, such as limestone and tuff are one of metallogenic material origins. Both of Pb model age and Rb-Sr isochrone research obtained older age value than that of strata, possibly for been influenced by hydrothermal transformation, and interfusion of ancient basis material.3、There are two kinds of main metallogenic fluid inclusion in barite of the Longtoushan ore deposit, which are rich gas phase(C type) and liquid phase (D type) . Their size is 2~7 um, and principal components is H2O. Both kinds fluid inclusion have freezing point temperature -7.1℃～-2.4℃and -5.5℃～-0.3℃, salinity 4.0~10.6wt% and 0.5~8.5wt%, homogeneous temperature 176.8℃～361.6℃and 101.4℃～279.9℃,which peak value around 270℃and 170℃, respectively. Density of the ore-forming fluid is 0.73～0.97g/cm3, and metallogenic pressure is 62.3×105～377.9×105Pa. Above characteristic of the fluid inclusion are well geared to that of ore deposit originated in seabed hot-water sedimentation.4、Through the comparison research, that Longtoushan ore deposit has main characteristics of hot-water sedimentation ore deposit has been indicated. Ore-forming control factor and prospecting symbol of it has been summarized, as well as metallogenic model and prospecting model. Next step work direction about prospecting has also been proposed finally.更多还原